HEAT oven to 350°F. Reserve 1/4 cup salsa for later use. Mix chicken, soup and VELVEETA until well blended; spread 1 cup onto bottom of 8-inch square baking dish.
TOP with layers of 6 tortilla halves and 1/2 each of the remaining remaining salsa and chicken mixture; repeat layers.
BAKE 30 to 35 min. or until heated through. Serve topped with reserved salsa.